Those who are having foot lights in their stairway, then acme663ryo has an interesting stuff for you. According to acme663ryo, your foot lights are having epoxy pools of glass in the knot holes. These can be triggered by any light motion sensor, which in turn drives a solid state relay. The relay during its active cycle switches your DC power supply ON and through which you can connect your LED lights.

In the above video, acme663ryo demonstrates his build with a Dell power supply driving 11.5 V to approximately 35 LED lights. More at YouTube.